Method of obtaining gasoline and other low-boiling-point distillates from heavier hydrocarbons



METHOD OF OBTAINING GASOLINE AND OTHER LOW BOILING POINT INVENTOR Hi5 ATTORNEYS DISTILLATES FROM HEAVIER HYDROCARBONS Flled Ann]. 17 1920 w k R 2 r n N Q .l l Nu a IMWWH kw Patented Aug. 18, 1925.

UNITED STATES PATENT OFFICE.

ARTHUR I). SMITH, OF ARKANSAS CITY, KANSAS.

METHOD OF OBTAINING GASOLINE AND OTHER LOW-BOILING-POINT DISTILLATES FROM HEAVIER HYDROCARIBONS.

Application filed April 17, 1920.

To all whom it may concern:

Be it known that I, ARTHUR D. SMITH, a citizen of the United States, and a resident of Arkansas City, in the county of Cowley and State of Kansas, have invented a new and useful Improvement in Methods of Obtaining Gasoline and Other Low-Boiling- Point Distillates from Heavier Hydrocarbons, of which the following is a specification.

This invention relates to a method of treating heavier hydrocarbons such as parafline distillate, gas oil and residuum to produce benzine, gasoline or other low boiling point derivatives.

The cracking of heavy hydrocarbons produces free carbon which either remains in the liquid in a colloidal condition or is deposited on the apparatus. It is well known that a coating of carbon precipitated on the apparatus shortens the life of the apparatus and otherwise produces very serious and disadvantageous efiects and that it is highly desirable to prevent such deposit of carbon.

I have discovered that the presence of free colloidal carbon in the liquid modifies the chemical reactions of the cracking process and that the composition of the resulting product varies with the amount of colloidal carbon present during the cracking operation.

The principal objects of the present invention are to minimize the deposition of carbon, to provide for eliminating the larger particles of suspended free carbon from the liquid, to provide for the control of the colloidal carbon content of the liquid and for correlating the same with the factors of temperature and pressure for prede- 4 termining the product, and to obtain other advantages hereinafter appearing. The invention consists principally in circulating the liquid through a still and centrifugally separating out a predetermined portion of the colloidal carbon before returning the liquid to the still, also in filtering out the larger particles of free carbon before centrifugally removing the colloidal carbon. It also consists in the process and steps hereinafter described and claimed.

In the accompanying drawing wherein like numerals refer to like parts wherever they occur,

Serial No. 374,571.

horizontal transverse drum 4 which latter is connected to the rectangular front leg 2 by a series of tubes, the horizontal rows of which are represented by 5, 6, 7, 8, 9 and 10, the number and size of which are determined by the capacity of the still. The upper rows of tubes are of smaller diameter than the lower rows in order to make them more effective in heating the oil and thus relieve the larger lower tubes of being overheated. The front leg 2 is fitted with hand hole caps 5, 6', 7, 8', 9 and 10 placed di rectly in front of the tubes to allow for renewal and inspection and cleaning as the occasion demands. The main shell 1 with its connecting legs and tubes is suspended over a fire box 11 the flue for which is shown at 12. A pyrometer 13, liquid level gauge 14, pressure gauge 15, entrance manholes 16 and 17 vapor line 18, vapor line control valve 18, condenser box and coil 19, and receiving tank 20 are also provided. A pipe 21 which connects to the lower extremity of the rear leg 3 of the still, is connected through control valves 22 to centrifuges 23 which are supported by the framework 24 and are propelled by any suitable means such as the steam turbines shown at 25. The outlet pipe 26 of the centrifuges 23 connects through the valves 27 to the lower transverse drum 4 of the still.

The still is further provided with a vertical shaft 27 a which is supported by suitable bearings at 28, 29 and 30 and rotated by any suitable means such as the pulley 31. The shaft 27 a is further provided with a filter which is constructed so as to whirl or rotate with the shaft 27 and as shown in the drawings, consists of an upper circular spider 32 and lower circular spider 33 which are secured to the shaft 27 so as to rotate with it. The spiders 32 and 33 serve to hold in place and revolve the concentric cylindrical screens 34 and 35. The concen- 2 1,oou,11a

tric cylindrical screens 34 and 35 are of different diameters with the space enclosed by their circumferences being filled with steel wool, fullers earth or any other suitable filtering or straining material 36.

The inner surface of the cylindrical screen 35 is provided with spirally shaped curved vanes 37 which, how-ever, may be attached to the shaft 27 instead of said screen. The shaft 27 enters the still shell 1 through the stuffing box 38 which is of the oil cooled type. The inner shell of the stuffing box 38 is provided with one or more holes 39 which allow for lubrication of the shaft 2* and also provide a simple and effective means of feeding and controling the oil entering the still shell.

The cooling and feeding oil is contained in the tank 40 and is pumped through the pipe 41 by the pump 42 through the pipe 43 into the stufling box 38 the excess leaving the stuffing box through the pipe 44 and the relief valve 45 returning to the tank 40, an initial charge being first pumped through the valve 51 to the still 1, to fill the latter up to the level indicated at 52. The lines 43 and 44 are connected by the line 46 through the automatic pressure regulating valve 47 which is operated through the pipe 48 by the pressure generated in the vapor space of the shell 1. The heavy bottoms which accumulate in the still are pumped out through the pipe 49 and valve 50 by a pump (not shown).

In the active operation of the above described apparatus, it is fired until incipient cracking of the charge begins, which under a low pressure usually means the formation of a slight quantity of free carbon which is liable to deposit unless prevented. Although such deposited carbon no longer chemically enters into any reaction, Inechanically it may obstruct the continuity of the process by burning on to the surfaces of the apparatus and clogging tubes, and therefore the centrifugal filter 32, 33, 34 and 35 is promptly started in order to eliminate the larger particles of free carbon from the liquid contents of the still. This filter will continue effective to eliminate the larger particles of free carbon being formed for many days after the colloidal control has been established. With the centrifugal filter in operation and the still building up temperature and pressure, tests are made on the contents of the still to determine the amount of colloidal carbon present therein and its tendency to precipitate and become chemically inactive. If from experience with a particular supply, the percentage at a given temperature and pressure indicates an imminent deposition of carbon with corresponding increased production of permanent gas, the centrifuges 23 are started, and the liquid. contents of the still are drawn through same until the content of colloidal carbon is reduced to the desired percentage. Fresh supplies of gas oil or the like are introduced from time to time into the circulation to replace the portion converted into low boiling point compounds; the heavy residue is withdrawn as may be necessary; and the amount of colloidal carbon is determined and corrected at regular intervals, so that the process is essentially continuous.

As a typical run, there might be instanced a still operating under a pressure of 140 pounds per square inch at 725 degrees Fahrenheit, with a ratio of 300 square feet of iron surface exposed to combustion gases to 80 barrels of oil, and a normal colloidal carbon content of 3 to 4 per cent. for this temperature and pressure. Such conditions will allow the production of naphtha of 53 degrees Baum of initial boiling point 108 degrees Fahrenheit of constant output and composition. Again, by operating say under 100 pounds pressure at 700 degrees Fahrenheit, practically the same results can be obtained by allowing colloidal carbon content to mount to 5 to 7 per cent. There is obviously a greater tendency for the colloidal carbon to deposit from semi-solution as its concentration rises, thus making lower temperature and pressure conditions more diflicult to control, while extremely high temperatures and pressures are of course limited by the physical strength of the metal of still; but over a wide range of temperatures and pressures, a colloidal carbon balance exists therefor.

It is noted in carrying out my process, the circulating charge is divided into a plurality of streams directly above the furnace, those that are exposed to the most intense heat being of the largest cross-sectional area, while those that are exposed to less intense heat are of smaller cross-section. The reason for this difference in the cross-section of the stream is that the greater the volume of liquid treated the greater the amount of heat required therefor and consequently by properly proportioning the amount of liquid in the respective streams with reference to the difference in the intensity of the heat, all of the liquid is submitted to substantially the same treatment. It is to be noted also that the liquid contents of the apparatus pass from the still through the mechanical filter to eliminate the larger particles of free carbon before being passed through the centrifuges which eliminate more or less of the colloidal carbon preparatory to returning the liquid either alone or replenished with a fresh supply to the tube system and still.

When it is desired to apply my process to the treatment'of crude oil or oils con taining a considerable percentage of light hydrocarbons, the light hydrocarbons up to and including the kerosenes are first preferably eliminated by any suitable method.

It is noted that so long as the conditions of temperature, pressure and colloidal content remain uniform, the products of a given supply are substantially uniform, but that the products vary more or less according to the variation of one or more of said factors. Accordingly, the colloidal content may be varied as a convenient means of producing changes in the resulting products, Without varying the temperature or pressure of operation.

WVhat I claim is:

1 1. The process of treating heavy hydrocarbons Which consists in cracking the same, filtering the remaining liquid to remove the larger particles of free carbon, then subjecting said liquid to centrifugal action to eliminate a portion of its colloidal carbon, and then returning said liquid to the cracking zone.

2. The improvement in the process of cracking heavy hydrocarbons which consists in maintaining a substantially constant content of colloidal carbon by eliminating during the cracking operation an amount of carbon substantially equal to the amount generated during said operation.

'3. The improvement in the process of cracking heavy hydrocarbons which consists in filter ng the liquid that leaves the crack ing ione to remove the larger particles of free carbon therefrom and then treating the same centrifugally to reduce its content of colloidal carbon and then returning said liquid to the cracking zone.

4:. The improvement in the process of cracking heavy hydrocarbons which consists in filtering the liquid that leaves the cracking zone to remove the larger particles of free carbon therefrom and then treating the same centrifugally to reduce its content of colloidal carbon to an amount that will give the fina'l'product desired and then returning said liquid to the cracking zone and introducing a fresh supply of the heavy hydrocarbon.

5. The improvement in the process of cracking heavy hydrocarbons which consists in filtering the liquid that leaves the cracking zone to remove the larger particles of free carbon therefrom and then treating the same centrifugally to reduce the content of colloidal carbon to an amount that will give the final product desired and then re turning said liquid to the cracking zone.

Signed at Arkansas City, Kansas, this 13th day of April, 1920.

ARTHUR D. SMITH. 

